Calcium carbide furnace tail gas waste heat boiler

Working principle

The gas in the calcium carbide furnace is mainly combustible gases such as carbon monoxide, hydrogen, and methane, accounting for about 90%. There are also coke particles in the smoke and dust, so direct combustion can be used to recover heat energy

The direct combustion method of calcium carbide furnace gas is to directly send the calcium carbide furnace gas as fuel into a gas waste heat boiler for combustion, which utilizes both the latent heat and sensible heat of the furnace gas to generate steam and then generate electricity. Due to the combustion of furnace gas in the boiler at a temperature of up to 1500 ℃, its dust is transformed into coarse and heavy non stick particles after calcination, no longer containing tar and cyanide ions. Most of the heat from the furnace gas is absorbed by the water-cooled wall tubes and the circulating tube bundles of the waste heat boiler of the calcium carbide furnace, and is sent to the dust collection equipment after reaching the appropriate exhaust temperature. Conventional cyclones, bag filters, and electrostatic precipitators can all meet the smoke and dust emission standards.

The waste heat utilization device of a calcium carbide furnace can generate electricity by using a boiler to produce steam, or by using an air preheater to produce hot air for other combustion devices in the enterprise to assist combustion, or as a heat source for material drying.

Calcium carbide furnace gas is mainly composed of combustible gases such as carbon monoxide, hydrogen, methane, etc. It is a high-value fuel. Nowadays, calcium carbide furnace enterprises have developed a comprehensive utilization process of waste heat from closed calcium carbide furnaces and white ash kilns. The calcium carbide furnace gas is input into the white ash kiln as a heat source for combustion, releasing its potential. However, due to the production process requirements of the white ash kiln, the input calcium carbide furnace gas must be clean. Therefore, the calcium carbide furnace gas needs to be dedusted using dry or wet methods before being input into the white ash kiln. This makes it a new issue to recover the sensible heat of the furnace gas before purification. Therefore, the non combustion method for recovering the thermal energy of the furnace gas has emerged

As mentioned earlier, the crude furnace gas of the calcium carbide furnace contains volatile substances. When the temperature is below 220 ℃, volatile substances can precipitate oily substances from the furnace gas, causing the oily substances to combine with the dust in the crude furnace gas and accumulate on the equipment, resulting in ash accumulation. Therefore, it is required that the exhaust temperature of the waste heat boiler of the calcium carbide furnace should not be lower than 220 ℃.

For the design of this type of calcium carbide furnace waste heat boiler, it is necessary to solve the difficulties of tar condensation under various working conditions, the difficulties of preventing and cleaning smoke and dust, and the problems of wear and dust accumulation on the pipe wall and timely cleaning of the furnace body caused by smoke and dust. Due to the fact that the gas temperature of the carbide furnace is between 400-600 ℃, reaching 1000 ℃ instantaneously, the heat exchange between the flue gas and the heating surface is mainly convective heat exchange. Therefore, the waste heat boiler of the carbide furnace is composed of convective tube bundles and does not require a radiative heat exchange surface.

Performance characteristics

1. The Zheng Guo internal combustion sealed calcium carbide furnace has a simple process, reliability, and maturity; One time investment saving, low maintenance workload; It has the advantages of small footprint, short construction period, and energy waste.

2. The fully enclosed calcium carbide furnace gas cooling device of Zhengguo has strong adaptability and strong control ability over the temperature of the cooled flue gas. On the one hand, it can separate tar in the collector, and on the other hand, it can prevent the bag from being burned due to high temperature.

3. On the one hand, bag filters can handle high temperature and high concentration flue gas, with high dust removal efficiency, ensuring high-quality gas sources. On the other hand, bag filters have high-strength dust cleaning capabilities, and Zhengguo uses the latest oil repellent and waterproof technology to reduce the infiltration of high-temperature resistant fibers and oils.

4. Install nitrogen seals between all pipeline flanges and use micro positive pressure conveying to prevent furnace gas leakage.

5. The flue gas adopts two-stage cooling measures. Firstly, a water-cooled sleeve is used to reduce the temperature of the flue gas to below 450 ℃. Then, it enters a forced cooler to cool down to 240 ℃ -280 ℃ to avoid tar precipitation. Once the flue gas exceeds the temperature limit, it can be released and nitrogen gas can be added to assist in cooling. Insulation measures should be taken for the conveying pipeline after dust removal to avoid tar precipitation and blockage of the pipeline.

6. Zhengguo integrates research and development, design, equipment operation, management, and control to find the optimal operating conditions and develop the best operating methods for specific user scenarios.

7. The tail gas waste heat boiler of a calcium carbide furnace is a waste heat recovery equipment that recovers the high-temperature, combustible, and ash containing tail gas heat energy generated by the calcium carbide furnace. The furnace is equipped with suitable dust removal equipment, which can significantly reduce the dust emissions from the tail gas of the calcium carbide furnace and alleviate or eliminate environmental pollution.

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